Abstract: An increasing proportion of children are born to parents who are unmarried at the time of the child?s birth. Children in such families, often termed ?fragile families?, are more likely to experience low father involvement or absence (LFIA) during childhood, which is in turn associated with a range of deleterious developmental outcomes. Despite the substantial scholarship on family processes, important questions remain about predictors of LFIA and about the family processes associated with LFIA. Using data on 5,102 racially diverse, low-income couples from the Building Strong Families (BSF) study, the studies proposed here aim to fill this gap by, first, testing a transactional model of couple relationship and co-parenting relationship quality, along with father involvement to examine how couple and parenting relationship dynamics are linked to LFIA (Aim 1). Secondly, we will examine how couple relationship, co- parenting, and parenting behaviors including LFIA are linked to children?s socio-emotional outcomes (Aim 2). Finally, we will examine variability in these processes based on (a) race- ethnicity, and (b) residential and non-residential father households (Aim 3). The proposed studies will provide advances in the understanding of family processes that are associated with LFIA and socio-emotional outcomes for children in fragile families, and provide targets for intervention to increase father involvement and promote children?s socio-emotional wellbeing. The proposed studies will include doctoral and masters level students at the Graduate School of Social Work, University of Denver, thus fulfilling the AREA R15 priority to provide students at an organization without substantial NIH funding with exposure to rigorous research and opportunity to participate in all aspects of the research process. This project will also strengthen the scientific environment at the applicant institution by promoting rigorous federally funded research among faculty.